Error during parsing. could not instantiate 'squeal.map.makecountalgq' with arguments 'null'

[Jonathan Coveney]

I did a search online, and while someone had the same error, I don't think
it was related. From the error log, I see this...

Caused by: java.lang.RuntimeException: Final function of
squeal.map.makecountalgq is not of the expected type.
        at org.apache.pig.EvalFunc.<init>(EvalFunc.java:146)
        at squeal.map.makecountalgq.<init>(makecountalgq.java:32)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native
Method)
        at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at java.lang.Class.newInstance0(Class.java:355)
        at java.lang.Class.newInstance(Class.java:308)
        at
org.apache.pig.impl.PigContext.instantiateFuncFromSpec(PigContext.java:472)

But here is my udf (I've truncated a bit, but it works if it isn't
algebraic)

public class makecountalgq extends EvalFunc<Map<String,Integer>> implements
Algebraic, Accumulator<Map<String,Integer>> {
        static TupleFactory mTupleFactory = TupleFactory.getInstance();
        static BagFactory mBagFactory = BagFactory.getInstance();
        private MapWrapper ourWrap = new MapWrapper();

        public String getInitial() { return Initial.class.getName(); }

        public String getIntermed() { return Intermed.class.getName(); }

        public String getFinal() { return Final.class.getName(); }

        //An initial tuple, crates partial results
        public static class Initial extends EvalFunc<Tuple> {
                public Tuple exec(Tuple input) throws IOException {
                        MapWrapper aWrap = new MapWrapper(new
HashMap<String,MutableInt>());
                        DataBag bag = (DataBag)input.get(0);
                        aWrap.addSBag(bag);
                        return mTupleFactory.newTuple(aWrap);
                }
        }
        //Called on the result of the Initial, or on another intermediate
        public static class Intermed extends EvalFunc<Tuple> {
                public Tuple exec(Tuple input) throws IOException {
                        return
mTupleFactory.newTuple(mergeWrappers((DataBag)input.get(0)));
                }
        }
        //Can take the tuple that initial or intermed creates
        public static class Final extends EvalFunc<Map<String,Integer>> {
                public Map<String,Integer> exec(Tuple input) throws
IOException {
                        return
mergeWrappers((DataBag)input.get(0)).convertMap();
                }
        }

        //takes a bag of MapWrappers and merges them
        public static MapWrapper mergeWrappers(DataBag bag) throws
IOException {
                Iterator<Tuple> bagIt = bag.iterator();
                MapWrapper aWrap = (MapWrapper)bagIt.next().get(0);
                while (bagIt.hasNext())
                        aWrap.merge((MapWrapper)bagIt.next().get(0));
                return aWrap;
        }
}

Any idea why I would get this error? It compiles fine, and if I even just
take out Algebraic, I can use the UDF (it just uses the accumulator). I
don't see how the type is off...

Any ideas? (in case the context matters: this is a script that takes a list
of (a, b:chararray), and gives you, for a given key, a map from b-># of
times b occured.

Here is how I invoke it:

register squeal.jar;
A = LOAD 'test.txt' AS (a:chararray, b:chararray);
B = GROUP A BY a;
C = FOREACH B GENERATE group, squeal.map.makecountalgq(A.b) as mapz;

And I get the error.

Thanks in advance. I guess I could content myself with an Accumulator but
the Algebraic solution is so close... a MapWrapper is a class I created that
lets me pass around Maps and whatnot.